Various degrees of palmitoylated guar galactomannan (PGGM) are prepared by a heterogeneous method. Both differential thermal analysis and X-ray diffraction spectra show substituted palmitoyl chains played a role in the new crystallization and the molecular aggregated structure of GGM was changed. Furthermore, the emulsifying properties of both water-soluble and oil-soluble PGGM were investigated in detail. It is demonstrated that PGGM has good emulsifying activity, even in high salt concentration or in acidic pH. In addition, the emulsifying properties of water-soluble PGGM-protein mixture was also studied systematically. It is proven that water-soluble PGGM is a kind of good oil in water (o/w) emulsion stabilizer. With water-soluble PGGM-casein mixture (0.1 wt %) as emulsifier, clove oil-water (v : v, 1 : 9) emulsion had good stability within 4 weeks at room temperature, and the breakage of emulsion was not brought about.